The present invention relates to terminal blocks and more particularly to a terminal block of the type which uses insulation displacement connector (IDC) terminal clips for terminating and interconnecting conductors such as telecommunications conductors.
Terminal blocks are utilized in the telecommunications industry to provide an interconnection point for the individual line pair conductors of multi-pair cables. Such terminal blocks may provide interconnections between cables from the central office and subscriber cables or interconnections between a central office cable and a multi-pair cable servicing a local area such as a housing subdivision. Terminal blocks intended for use indoors generally utilize insulation displacement connector (IDC) terminal chips. This type of connector automatically pierces the insulation of a portion of the wire to establish an electrical connection when the wire is inserted in the connector by means of a suitable tool.
One particularly useful terminal block of this type is illustrated and described for example in prior U.S. Pat. No. 4,652,070. This patent discloses a terminal block which advantageously utilizes activators which are captively mounted in the terminal block and associated with each IDC terminal clip to accomplish connection of a conductor with the clip, in place of the special hand tool normally required for this purpose. While this type of terminal block has found widespread acceptance there remains room for further improvement. For example, a second wire connection to each terminal clip in blocks of this type is accomplished by a wire wrap operation. Thus, the opposite end of the terminal clip generally comprises a wire wrap post which projects outwardly toward the opposite side of the terminal block. Generally speaking, terminal blocks of this type are preconnectorized. That is, an appropriate cable stub is provided, having its respective conductors factory prewired to the respective wire wrap terminals of the terminal clips within the block. However, such factory prewiring of cable stubs to the block is relatively labor intensive and hence expensive.
Terminal blocks are also known in which the terminal clips comprise bi-ended insulation displacement type clips. That is, both ends of the terminal clip are of the IDC type in which a conductor's insulation is pierced to establish electrically conductive contact with the clip, when the conductor is pressed into the clip by the use of a suitable tool designed for this purpose. Terminal blocks having such bi-ended or oppositely outwardly facing IDC type terminal clips are shown for example in prior U.S. Pat. Nos. 4,059,331 and 4,106,837.
Other terminal blocks are "one-sided" and use IDC's having multiple clips extending from a common base to accommodate all wire connections on the same side of the block. Such terminal blocks are shown for example in prior U.S. Pat. Nos. 3,957,335 and 5,127,845.
It is to be noted that in the above-mentioned '331 and '837 patents, each of the IDC terminal clips is assembled with the block by a press fitting operation in which the IDC terminal clip must be pressed into position within the block. In the above-mentioned '070 patent, the IDC terminal clip may be accurately longitudinally positioned within a mounting slot by providing an outwardly projecting shoulder on the clip which is pressed into engagement or seated with respect to a complementary projecting shoulder in a recess or cavity within the block. This patent also suggests that the IDC is to be "wedged" into its aperture in the block. However, it is important that the terminal clip be retained against movement in response to the pressure of the activator or other tool when pressing a wire conductor into the IDC clip portion with a force sufficient to achieve piercing of the conductor and electrically conductive contact with the IDC terminal clip. In such a press-fitting or "wedging" operation, a uniform and repeatable dislodgement or pushout force cannot always be predicted. For example, the metal terminal may strip or damage portions of the plastic block upon insertion, resulting in poor seating and insufficient force of engagement therebetween. Also, the IDC clip may not always be inserted in the correct alignment or orientation, or to the correct depth within the block.
In the case of double or bi-ended IDC clips as in the above '331 and '837 patents, it may also be difficult to assure that the terminal clip is properly centered within the block as a result of the press fitting operation. Moreover, this press fitting operation requires the use of special tools, special processing steps, etc. and thus adds to the expense of production and assembly of terminal blocks of this type.
As mentioned hereinabove, in prior U.S. Pat. Nos. 4,957,335 and 5,127,845 there is shown and described an IDC terminal block of the type in which the terminals project from only one side of the block. Interconnections are accomplished by means of multiple IDC's projecting from a single base portion. This base portion is mounted within the block by providing a separate back panel or cover which is suitably affixed to a rear surface of the block following the disposition of the terminals within suitable slots or cavities in the block. However, this construction and technique is not applicable in the case of bi-ended or oppositely outwardly projecting IDC clips of the type shown for example in the '331 and '837 patents, or for that matter the terminal clip of the type shown in the '070 patent, which has a wire wrap post projecting oppositely of the IDC portion.